Semiconductor device

ABSTRACT

The present invention provides a semiconductor device having a stacked structure which realizes the miniaturization of a contour size and the reduction of thickness. The present invention also provides a semiconductor device which realizes high performance and high reliability in addition to the miniaturization of the contour size. The semiconductor device uses a package substrate on which bonding leads which are formed respectively corresponding to bonding pads for address and data which are distributed to opposing first and second sides of a memory chip and address terminals and data terminals which are connected to the bonding leads are formed. The semiconductor device further includes an address output circuit and a data input/output circuit which are also served for memory access and a signal processing circuit having a data processing function. A semiconductor chip in which bonding pads which are connected to the bonding leads corresponding to the address terminals of the package substrate and bonding pads which are connected to the bonding leads corresponding to the data terminals of the package substrate are distributed to two sides out of four sides and the above-mentioned memory chip are mounted on the package substrate in a stacked structure.

BACKGROUND OF THE INVENTION

The present invention relates to a semiconductor device, and moreparticularly to a technique which is effectively applicable to asemiconductor device in which a plurality of semiconductor chips aremounted on a package substrate in a laminated or stacked structure, forexample.

In a stacked LSI (Large-sized Integrated Circuit) which assemblessemiconductor chips on a package substrate in a laminated or stackedstructure, existing semiconductor chips are combined in many cases andcommon signals and power source/ground are connected via wiring layersof a package. Due to a prior art search which is carried out after thepresent invention was made, as a prior art related to the presentinvention, a technique disclosed in Japanese Unexamined PatentPublication 43531/2000 is reported. However the technique disclosed inthis publication aims at the reduction of time and efforts necessary fordesigning and development of types of standard package LSI and lacksdeliberation to miniaturizing of the package and thinning of a contoursize of the package substrate which will be explained later.

SUMMARY OF THE INVENTION

With respect to the common signals and power source/ground in two chipswhich constitute the stacked package LSI, their pads are not alwaysarranged to positions where they can be connected easily between thechips. Accordingly, even when the wiring layers are connected on thepackage substrate, in many cases, there exist crossing wiring layers orwiring layers are arranged densely. In these cases, the number of wiringlayers of the package substrate is increased or a contour size isincreased thus obstructing the miniaturization and thinning of thesemiconductor device. Since connection terminals of mounting chips areformed individually, a large terminal arrangement area becomes necessaryand this also becomes a cause of increasing the contour size of thepackage.

FIG. 19 to FIG. 21 show examples of stacked package LSI which isreviewed prior to arriving at the present invention. A microcomputer LSIand a memory LSI are respectively constituted of existing semiconductorchips. In FIG. 19, the microcomputer LSI, the memory LSI and a packagesubstrate which constitute the stacked package LSI are respectivelyshown. The microcomputer LSI and the memory LSI are respectivelyconstituted of the existing semiconductor chips. FIG. 20 shows anappearance of the stacked package LSI after mounting the memory LSI andthe microcomputer LSI onto the substrate and, thereafter, performingbonding wiring. FIG. 21 a cross-sectional view of the stacked packageLSI shown in FIG. 20.

As shown in FIG. 19 to FIG. 21, the stacked package LSI adopts thestructure which is formed as follows. The memory LSI is die-bonded tothe package substrate made of glass epoxy-based resin. Then, themicrocomputer LSI is die-bonded to the memory LSI in a superposed mannerand respective chips and the substrates are connected to each other bywire bonding. Thereafter, these components are molded by resin andsolder balls are formed on back-surface terminal portions.

In FIG. 19, address terminals and data terminals which are connectedwith memories or the like are collectively arranged at sides of themicrocomputer LSI which are disposed close to each other. Due to such aconstitution, when the microcomputer LSI, the memory LSI and the likeare mounted on the substrate in plane, it is possible to arrange anaddress bus and a data bus directed to the memory and the like on thesubstrate with the shortest distance therebetween and in a collectivemanner. On the other hand, with respect to the memory LSI, in view ofthe characteristics thereof that the number of terminals is small andcorresponding to the external terminal arrangement of a standardpackage, the address terminals are mainly arranged at one side and thedata terminals are arranged at another side which faces one side in anopposed manner.

When the above-mentioned microcomputer LSI and memory LSI on which thebonding pads are arranged respectively are stacked or laminated to thepackage substrate and the directions of the address terminals of themicrocomputer LSI and the memory LSI are aligned, for example, thedirections of data terminals of the microcomputer LSI and the memory LSIare not aligned and hence, it is necessary to pull around wiring layerson the package substrate for wiring connection. Further, also withrespect to the aligned address terminals, the pitch of bonding padarrangement differs between the microcomputer LSI and the memory LSI andhence, it may be necessary to form terminals on the microcomputer LSIand the memory LSI independently from each other in most cases.

Accordingly, in the package substrate, the number of bonding terminals(bonding leads) is increased and hence, the bonding leads cannot bearranged in a row and it is necessary to arrange the bonding leads intwo rows as in the case of the example shown in FIG. 20. This arises adrawback that the contour size of the package substrate is enlarged.Further, depending on the arrangement of terminals of the microcomputerLSI and the memory LSI to be connected to each other, there arises acase in which wiring layers on the package substrate cross each otherand hence, it is necessary to provide a multi-layered printed wiringboard. This also gives rise to a drawback that the thickness as one ofcontour sizes is also increased.

It is an object of the present invention to provide a semiconductordevice having the stacked structure which can realize miniaturizationand thinning of contour sizes.

It is another object of the present invention to provide a semiconductordevice which can realize high performance and high reliability inaddiction to the miniaturization of the contour size. Theabove-mentioned and other objects and novel features of the presentinvention will become apparent from the description of thisspecification and attached drawings.

To briefly describe the summary of typical inventions out of inventionsdisclosed in the present invention, they are as follows.

According to one aspect of the present invention, a semiconductor deviceuses a package substrate which includes bonding leads which are formedrespectively corresponding to bonding pads for address and bonding padsfor data which are distributed to a first side and a second side of amemory chip facing each other in an opposes manner, and addressterminals and data terminals which are connected to the bonding leads. Asemiconductor chip includes an address output circuit and a datainput/output circuit which are also served for memory access and asignal processing circuit having a data processing function, wherein thebonding pads which are connected to the bonding leads corresponding tothe address terminals and the bonding pads which are connected to thebonding leads corresponding to the data terminals are distributed to andarranged on two sides out of four sides of the package substrate. Thesemiconductor chip and the memory chip are mounted on the packagesubstrate in a stacked structure.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a view showing the constitution of a microcomputer LSI, amemory LSI and a package substrate for explaining one embodiment of astacked package LSI according to the present invention.

FIG. 2 is an appearance view of the semiconductor device after mountingthe memory LSI and the microcomputer LSI on the substrate shown in FIG.1 and performing wire bonding thereafter.

FIG. 3 is a cross-sectional view of one embodiment of the stackedpackage LSI shown in FIG. 2.

FIG. 4 is a top plan view showing another embodiment of the packagesubstrate used by the present invention.

FIG. 5 is a top plan view showing another embodiment of the packagesubstrate used by the present invention.

FIG. 6 is an appearance view of the semiconductor device after mountingthe memory LSI and the microcomputer LSI on the substrate shown in FIG.5 and performing wire bonding thereafter.

FIG. 7 is a top plan view showing another embodiment of the packagesubstrate used by the present invention.

FIG. 8 is an appearance view of the semiconductor device after mountingthe memory LSI and the microcomputer LSI on the substrate shown in FIG.7 and performing wire bonding thereafter.

FIG. 9 is a top plan view showing another embodiment of the packagesubstrate used by the present invention.

FIG. 10 is an appearance view of the semiconductor device after mountingthe memory LSI and the microcomputer LSI on the substrate shown in FIG.9 and performing wire bonding thereafter.

FIG. 11 is a partial appearance view showing another embodiment of thesemiconductor device according to the present invention.

FIG. 12 is a partial appearance view showing another embodiment of thesemiconductor device according to the present invention.

FIG. 13 is a partial appearance view showing another embodiment of thesemiconductor device according to the present invention.

FIG. 14 is a block diagram showing one embodiment of a microcomputer LSIused in the present invention.

FIG. 15 is a view schematically showing an arrangement of pins forexplaining one embodiment of the microcomputer LSI in FIG. 14.

FIG. 16 is an appearance view after mounting the memory LSI and themicrocomputer LSI on the substrate of one embodiment of thesemiconductor device according to the present invention and performingwire bonding thereafter.

FIG. 17 is a partially enlarged view of FIG. 16.

FIG. 18 is a top plan view showing one embodiment of the packagesubstrate used in the semiconductor device shown in FIG. 16.

FIG. 19 is a view showing the constitution of a microcomputer LSI, amemory LSI and a package substrate for explaining one embodiment of astacked package LSI which is reviewed prior to the present invention.

FIG. 20 is an appearance view of the semiconductor device after mountingthe memory LSI and the microcomputer LSI on the substrate shown in FIG.19 and performing wire bonding thereafter.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

In FIG. 1 to FIG. 3, the constitution of one embodiment of a stackedpackage LSI according to the present invention is shown. That is, inFIG. 1, a microcomputer LSI, a memory LSI and a package substrate whichconstitute the stacked package LSI are respectively shown. In FIG. 2, anappearance of the stacked package LSI in a state that the memory LSI andthe microcomputer LSI are mounted on the substrate and, thereafter, thewire bonding is performed is shown. FIG. 3 shows the cross section ofthe stacked package LSI. As shown in FIG. 1 to FIG. 3, the stackedpackage LSI of this embodiment has the structure which is formed asfollows. That is, the memory LSI is die-bonded to the package substratemade of glass epoxy resin. Then, the microcomputer LSI is superposed onand is die-bonded to the memory LSI. Wire bonding is performed betweenthe respective chips and the substrate. Thereafter, the respective chipsand the substrate are molded with resin and solder balls are formed onback-surface terminal portions.

In FIG. 1, while the memory LSI is constituted of an existingsemiconductor chip, the arrangement of bonding pads of the microcomputerLSI is determined corresponding to the memory LSI which is combined withthe microcomputer LSI. The microcomputer LSI is configured to constitutea so-called ASIC (Application Specified Integrated Circuit), that is, aspecific-use IC. In the semiconductor integrated circuit device, toeasily constitute the ASIC in which a plurality of circuit blocks aremounted around a CPU (central processing unit), respective circuitblocks are formed into so-called modules or macro cells as independentcircuit functional units. The magnitude and constitution of eachfunctional unit can be changed. Setting of the arrangement of thebonding pads of the microcomputer LSI corresponding to theabove-mentioned combination of the microcomputer LSI with the memory LSIis performed along with layout designing of the functional blockscorresponding to the combination of the above-mentioned functionalunits.

With respect to the package substrate (wiring substrate), thearrangement of boding leads (wire connecting portions) is setcorresponding to the arrangement of the above-mentioned bonding padsbetween the microcomputer LSI and the memory LSI. The above-mentionedpackage substrate includes a base substrate made of glass epoxy resin,for example, a plurality of copper wiring layers which are formed on anupper surface and a lower surface thereof, insulation films (solderresist films) which cover surfaces of the above-mentioned plurality ofcopper wiring layers at portions other than the above-mentioned wireconnecting portions and external terminal connecting portions (bumplands), and through-hole wiring layers which connect a plurality ofcopper wiring layers formed on the above-mentioned upper surface andlower surface to each other.

The memory LSI is, although it is not particularly limited, a statictype RAM which has a storage capacitance of approximately 8 Mbits. Theshape of the semiconductor chip is formed into a rectangular shape andaddress and data are distributed to short sides where bonding pads areformed. Compared to the memory LSI having such a constitution, themicrocomputer LSI has a substantially square chip shape and has acontour size smaller than that of the above-mentioned LSI. Accordingly,as mentioned above, the stacked package LSI is constituted such that thememory LSI is die-bonded to the package substrate, the microcomputer LSIis superposed on and is die-bonded to the memory LSI, and wire bondingis performed between respective chips and the substrate.

To reduce the contour size, the above-mentioned package substrate isformed into a substantially square shape to ensure the largest area withrespect to the outer circumference. In such a constitution, there existsno area margin at the short sides of the memory LSI and hence, thebonding leads which are indicated by a rectangular shape are arrangedalong the outer circumference, and the pullout direction of wiringlayers reaching the through holes is directed to the inside of thepackage substrate. With respect to the bonding leads which correspond tothe above-mentioned address and data through holes corresponding to thebonding leads are arranged at the inside of the substrate. On thecontrary, since there exists area margin at long sides of the memoryLSI, the through holes are arranged such that they are distributedalternately at both sides of the bonding leads to sandwich the bondingleads.

As described above, in the microcomputer LSI, the address terminals andthe data terminals are arranged in a concentrated manner on the sideswhich face each other. Further, a group of terminals which do notcontribute to the connection with the memory LSI are mainly arranged onsides other than the above-mentioned sides. Accordingly, the possibilitythat the directions of terminals which are connected to each other arenot aligned even when the microcomputer LSI is stacked on the memory LSIis eliminated. Further to prevent the wires from crossing each other ina complicated manner at the time of performing stacking and bonding, themicrocomputer LSI has a pitch thereof adjusted in conformity with apitch of the terminals of the memory LSI. That is, compared to a case inwhich the wires cross each other in a complicated manner, that is, acase in which three wires are superposed in the vertical direction asshown in FIG. 21, for example, a case in which two wires are superposedby eliminating crossing as shown in FIG. 3 can reduce a thickness of amold (sealed resin body).

Although the above-mentioned pitch adjustment can be performed by simplyadjusting the distance, in this embodiment, the pitch adjustment isperformed by arranging terminals having other functions to the row ofaddress terminals or the row of data terminals. Since the pitchadjustment is performed in this manner, the terminals of themicrocomputer LSI and the terminals of the memory LSI which are to beconnected to each other can be bonded to the same substrate-side pads,whereby it is unnecessary to pull around wiring layers for connectingbetween the terminals on the package substrate. As a result, it isenough for the package substrate to have wiring connection from thebonding leads to ball terminals for external connection and hence, thesufficient required functions can be performed by the two-layered wiringlayers formed on a front surface and a back surface of the substrate.The constitution provided with such a pitch adjustment contributes tothinning of the stacked package LSI along with thinning of theabove-mentioned mold. Since the bonding leads are substantially used incommon by the microcomputer LSI and the memory LSI, the number of leadscan be suppressed to a necessary minimum whereby the contour size can beminiaturized.

With respect to the leads of the sides which are bonded in common by themicrocomputer LSI and the memory LSI, the length of the leads iselongated such that the wires which are directed and connected to themicrocomputer LSI and the memory LSI can be bonded in parallel in thevertical direction. On the other hand, as in the case of the bondingleads which correspond to the long sides of the memory LSI, the leads onthe sides to which only the microcomputer LSI is bonded, is retained toa length which allows bonding of one wire thus preventing the wiringlayer region from becoming large more than necessary.

Although the length of the bonding leads is changed in accordance withevery side in this embodiment, the length of the bonding leads may bechanged in accordance with a plurality of leads to be bonded withoutchanging the length of the bonding leads in accordance with every side.Another characteristics of this embodiment related to theminiaturization lies in that, since the memory chip has a rectangularshape as described above, the side on which the bonding leads of thememory chip are arranged has no margin in the contour size, whereby thebonding leads are arranged at the outermost circumference and thethrough holes are arranged to be directed to the inner circumference. Onthe other hand, with respect to the sides to which only the microchip isbonded, the through holes are arranged such that they are distributed tothe inside and the outside of the bonding leads.

FIG. 4 is a top plan view showing another embodiment of the packagesubstrate used in the present invention. In the above-mentionedembodiment shown in FIG. 1, the addresses or data of the memory LSI andthe microcomputer LSI are completely arranged on the same sides.However, in view of the relationship with the layout of the chips, theaddresses and the data are not always concentrated on the sides whichface each other in an opposed manner. Further, even when the addressesand data are completely separated at the sides which face each other inan opposed manner, signals for control, for example, control signalssuch as read/write signals, chip select signals and output enablesignals which the microcomputer and the memory use do not always agreewith each other.

In this embodiment, with respect to the microcomputer LSI and the memoryLSI, when the same terminals or the terminals (bonding pads) to beconnected with each other are arranged on the sides which face eachother in an opposed manner, wiring layers which bridge the opposingsides are formed on the substrate. By concentrating the most signals(addresses and data) to be connected to each other by the microcomputerLSI and the memory LSI to the same sides, the number of bridging wirelayers can be minimized. Accordingly, it is possible to sufficientlyperform the required function using two-layered wiring which are formedon the front surface and the back surface of the substrate.

FIG. 5 is a top plan view of another embodiment of the package substrateused in the present invention. This embodiment is directed to the shapeof the bonding leads. The embodiment shown in FIG. 5 shows an example ofthe package substrate in which the rectangular bonding leads arearranged in the same manner as the embodiment shown in FIG. 1. FIG. 6shows an appearance of a stacked package LSI in which a memory LSI and amicrocomputer LSI are mounted on a package substrate in a stackedmanner. The embodiment shown in FIG. 6 also corresponds to theembodiment shown in FIG. 2.

In this embodiment, with respect to bonding leads which perform wirebonding in common between the memory LSI and the microcomputer LSI, tobond at least two wires to the bonding lead, it is necessary to connectwires of the microcomputer LSI to the deep side of the lead (outside ofthe lead). Then, as a result of the arrangement in which the bondingpads of the microcomputer LSI are arranged collectively at portionsclose to the center of the substrate, the wires are directed in theradial direction such that they are concentrated at positions close tothe center of the substrate. As a result, there arise portions of thewires which pass over another neighboring leads thus giving rise to aproblem that the potential of short circuiting between the neighboringlead and the wire is high.

FIG. 7 is a top plan view showing another embodiment of the packagesubstrate used in the present invention. This embodiment is directed toa method for obviating the problem that there arise portions of wireswhich are bonded while passing over another neighboring leads as in theembodiment shown in FIG. 5. In this embodiment, by taking the directionof wires which are served for connection between the bonding leads andthe corresponding bonding pads of the microcomputer LSI and the memoryLSI into consideration, the bonding leads are arranged in an obliquemanner. FIG. 8 shows an appearance of a stacked package LSI in which thememory LSI and the microcomputer LSI are mounted on the packagesubstrate in a stacked manner and wire bonding is performed thereafter.

In FIG. 8, with respect to the bonding leads which perform bonding incommon with respect to the memory LSI and the microcomputer LSI, atleast two wires are arranged in a radial direction such that they aredirected toward the corresponding bonding pads of the microcomputer LSIand the memory LSI. Here, by making this direction and the longitudinaldirection of the bonding leads substantially identical to each other, itis possible to eliminate portions of the wires which are bonded whilepassing over another neighboring leads. Further, at the same time, it ispossible to prevent the wires from crossing each other in a complicatedmanner so that only two wires at the maximum which correspond to themicrocomputer LSI and the memory LSI are superposed each other whereby athickness of a mold can be reduced.

FIG. 9 is a top plan view showing another embodiment of the packagesubstrate used in the present invention. This embodiment is directed toa method for obviating the problem that there arise portions of thewires which are bonded while passing over another neighboring leads asin the embodiment shown in FIG. 5. In this embodiment, portions of theneighboring leads over which the wires pass are notched and hence, it ispossible to shorten a pitch of the leads to a necessary minimum whilereducing the potential of short-circuiting between the neighboring leadsand the wires. FIG. 10 shows an appearance of a stacked package LSI inwhich the memory LSI and the microcomputer LSI are mounted on thepackage substrate in a stacked manner and wire bonding is performedthereafter.

In FIG. 10, as mentioned previously, with respect to the bonding leadswhich perform bonding in common with respect to the memory LSI and themicrocomputer LSI, at least two wires are arranged in a radial directionsuch that they are directed toward the corresponding bonding pads of themicrocomputer LSI and the memory LSI and hence, it is necessary toconnect the wires of the microcomputer LSI to the deep side of thebonding lead (outside of the bonding lead). As a result, there ariseportions of the wires which are bonded while passing over anotherneighboring leads and hence, the potential of short-circuiting betweenthe neighboring lead and the wire is increased. However, in thisembodiment, the portion of the leads over which the neighboring wirespass are notched and hence, it is possible to obviate a drawback onshort-circuiting between the neighboring leads and the wires.

FIG. 11 is a partial appearance view of another embodiment of thesemiconductor device according to the present invention. In thisembodiment, a portion of the appearance when one semiconductorintegrated chip LSI is mounted on a package substrate is shown in anillustrated manner. In this embodiment, with respect to thesemiconductor chip mounted on the package substrate, one semiconductorchip LSI is mounted. It is needless to say that this embodiment isapplicable to the structure in which another semiconductor chip ismounted on the semiconductor chip LSI in a stacked manner.

This embodiment is applicable to a case in which the number of bondingpads formed on the semiconductor chip LSI is large and hence, thebonding leads can not be arranged in a row on the substrate. In thiscase, the bonding leads are arranged in two rows, wherein the inside rowand the outside row are alternately arranged thus constituting aso-called staggered arrangement. This embodiment is provided foreliminating the superposition of the neighboring wires which connect thebonding leads and the bonding pads and for ensuring regions for formingwiring layers which extend from outside bonding leads to the throughholes formed inside.

FIG. 12 is a partial appearance view showing another embodiment of thesemiconductor device according to the present invention. This embodimentrelates to an improvement of the embodiment shown in FIG. 11, wherein aportion of the appearance of the semiconductor device in a state thatone semiconductor chip LSI is mounted on the package substrate is shownin an illustrated manner. In the embodiment shown in FIG. 11, therearise portions of the wires which extend from the outside bonding leadsand are bonded while passing over another leads in the inside and hence,there is a possibility that the potential of short-circuiting betweenthe inside leads and the wires is increased.

In this embodiment, to obviate such a drawback, by considering thedirection of the wires which are served for connecting the bonding leadsand the corresponding pads of the semiconductor chip LSI, the bondingleads are arranged in an oblique manner. By arranging the bonding leadsand the wires which are connected to the bonding leads in the radialdirection such that they are aligned substantially in the samedirection, it is possible to eliminate portions where the wires arebonded while passing over another leads disposed inside. Further, at thesame time, it is possible to eliminate crossing of the wires to eachother and hence, short circuiting of the wires can be prevented and thethickness of a mold can be reduced.

FIG. 13 is a partial appearance view of another embodiment of thesemiconductor device according to the present invention. This embodimentrelates to an improvement of the embodiment shown in FIG. 12. In FIG.13, a portion of the appearance of the semiconductor device when onesemiconductor chip LSI is mounted on a package substrate is shown in anillustrated manner. In the embodiment shown in FIG. 12, when the leadsare arranged in a multiple rows and the inclination of the leads isaligned to the wire direction, as the leads extend toward the outside,the distance between leads is widened. On the contrary, the distance atcorner portions of the inner leads is narrowed and hence, there arises acase that the wiring layers extending from the outside leads to thethrough holes can not pass over. To obviate such a drawback, in thisembodiment, inner circumferential corner portions of the leads which areexpanded in the radial direction are notched so as to ensure the spacehaving a width necessary for allowing the wiring layers to pass. Due tosuch a constitution, it is possible to pull around the wire layerswithout expanding the bonding area more than necessary.

FIG. 14 is a block diagram showing one embodiment of a microcomputer LSIused in the present invention. Respective circuit blocks in the drawingare formed on one substrate made of single crystalline silicon using aknown fabrication technique of CMOS (complementary MOS) semiconductorintegrated circuits.

Although the above-mentioned microcomputer LSI is not specificallylimited, the microcomputer LSI realizes high-performance arithmeticprocessing using a RISC (Reduced Instruction Set Computer) type centralprocessing unit CPU, integrates necessary peripheral equipment forsystem constitution and is directed to portable equipment application.The central processing unit CPU has a command set of RISC type, whereinbasic commands are operated at 1 state by 1 command (1 system clockcycle) by performing the pipe-line processing. Using these centerprocessing unit CPU and data signal processor DSP mainly, followingperipheral circuits are mounted to constitute a mobile telephone set,for example.

The inner bus includes an I bus, a Y bus, an X bus, an L bus andperipheral buses. To constitute a user system using a least number ofparts, as built-in peripheral modules, a memory XYMEM which is directedto image processing and a memory controller XYCNT are provided. Thesememory XYMEM and memory controller XYCNT are connected to the I bus, theX bus, the Y bus and the L bus and data inputting/outputting of imageprocessing and data outputting operation for display operation areperformed.

In the above-mentioned I bus, a cache memory CACHE, a cache memorycontroller CCN, a memory management controller MMU, a translationlook-aside buffer TLB, an interrupt controller INTC, a clockoscillator/watch dog timer CPG/WDT, a video I/O module VIO and anexternal bus interface are provided. These are connected with theabove-mentioned memory LSI via the external bus interface.

To the L bus, the cache memory CACHE, the cache memory controller CCN,the memory management controller MMU, the translation look-aside bufferTLB, the central processing unit CPU, data signal processor DSP, a userbreak controller UBC and an advanced user debugger AUD are connected.

To the peripheral bus, a 16-bit timer unit TMU, a compare match timerCMT, a serial I/O (with FIFO) SIOFO, a FIFO built-in serialcommunication interface SCIF1, an I²C controller I²C, a multi-functionalinterface MFI, a NAND/AND flush interface FLCTL, a user debug interfaceH-UDI, an ASE memory ASERAM, a pin function controller PFC, and a RCLKoperation watch dog timer RWDT are connected. To the above-mentionedperipheral bus and the I bus, a bus state controller BSC and a directmemory access controller DMAC are connected.

FIG. 15 is a view showing the approximate pin arrangement of oneembodiment of the microcomputer LSI shown in FIG. 14. In thisembodiment, while there are provided 176 pieces of pins (bonding pads)in total, the pins which are connected to the memory LSI are indicatedby black dots. In the same manner as the microcomputer LSI shown in FIG.1, the pins which correspond to addresses and data are arranged suchthat they are distributed to upper and lower sides which face each othervertically. In this embodiment, the pins corresponding to data arearranged on the upper side and the pins corresponding to the addressesare arranged on the lower side. To match a pitch of the correspondingpins (bonding pads) of the memory LSI on which the microcomputer LSI ismounted, pins which are connected only to the microcomputer LSI aresuitably arranged between the black-dotted pins which are connected tothe above-mentioned LSI.

Although not shown in the drawing, with respect to the pins provided tothe microcomputer LSI, the pins A0 to A25 are served for addresses andD0 to D15 are served for data. Besides the above, as a power sourcesystem, a plurality of power source voltages VCC and a plurality ofground potentials VSS are provided respectively. In the power sourcesystem, a digital circuit for reducing an influence of noises is dividedinto an output circuit for performing outputting of signals to externalterminals and an inner circuit. Further, independent power source pinsare provided for a circuit which handles analogue signals.

The memory LSI has storage capacitance of approximately 8 Mbits andperforms a memory access per 16 bits and hence, the address includes 19bits from A0 to A18. Although the microcomputer LSI includes 26addresses A0 to A25, the addresses which are connected in common withthe microcomputer LSI and the memory LSI are 19 pieces and hence, thenumber of addresses becomes 19+16=35 pieces including addresses fordata.

Although not particularly limited, as control signals which areconnected in common, there are provided four signals consisting of asignal WE (write enable), a signal OE (output enable), a signal US(upper select) and a signal LS (low select). The signal US is served forinstructing writing of upper 8 bits out of 16-bit data and the signal LSis served for instructing writing of lower 8 bits out of 16-bit data.Accordingly, the number of pins which are connected in common by themicrocomputer LSI and the memory LSI is small, that is, 39 pieces intotal. Accordingly, to match the arrangement of the pins which areconnected in common in the above-mentioned manner in the memory LSI, inthe microcomputer LSI, the bonding pads for data and the bonding padsfor address are arranged in a skipped manner as indicated by black dotsin the drawing.

FIG. 16 shows an appearance of one embodiment of the semiconductordevice according to the present invention in a state that the memory LSIand the microcomputer LSI are mounted on the substrate and, thereafter,wire bonding is performed. In this embodiment, the stacked package LSIon which the microcomputer LSI which is explained in conjunction withFIG. 14 and FIG. 15 and the memory LSI formed of an approximately 8 Mbits SRAM are mounted is shown. In the drawing, balls formed on a backsurface of the package substrate are indicated by white dots.

In this embodiment, out of the bonding leads mounted on the substrate,with respect to the bonding leads which are matted in black, the wiresextend from these bonding leads to the memory LSI and the microcomputerLSI and are connected in common. FIG. 17 is a partial enlarged view,wherein the bonding leads are arranged obliquely along the extensiondirection of the wires such that the wires extending toward the memoryLSI and the microcomputer LSI from the bonding leads do not cross eachother. First, this constitution prevents the wires extending from theneighboring leads from crossing above the bonding leads.

FIG. 18 is a top plan view of one embodiment of the package substrateused in the semiconductor device shown in FIG. 16. The bonding leadswhich include the data terminals and address terminals of theabove-mentioned memory LSI and the microcomputer LSI are formed on theupper side and a lower side of the substrate. The bonding leads whichare formed on the upper and lower sides are arranged along the outermostcircumference. On the other hand, with respect to the bonding leadswhich are connected to only the microcomputer LSI, the through holes areformed in a dispersed manner at the left and the right with respect tothe bonding leads. That is, in the left and right sides, the throughholes are formed at the outermost circumference. The number of thethrough holes which are dispersed to the left and right with respect tothe above-mentioned bonding leads is not univocally alternately anduniformly divided as in the case of the embodiment shown in FIG. 1. Thatis, the number of the through holes is suitably determined byconsidering the space over the substrate.

In the above-mentioned embodiment, it is possible to suppress the pullaround of wiring layers on the substrate package to a minimum and hence,it is possible to make the contour size as small as possible. Due to theelimination of crossing wiring layers, the connection of package wiringlayers can be performed at both of the front and rear layers and hence,it is possible to use the thin and inexpensive substrate. Further, it isalso possible to reduce the thickness of the mold portion by suppressingcrossing of wires. Incidentally, when the semiconductor device isconstituted as shown in FIG. 19 which is studied prior to the presentinvention, LFBGA can be obtained only at a level of 1.4 mm square.According to the constitution shown in FIG. 16, it is possible torealize the semiconductor device which is smaller than the semiconductordevice shown in FIG. 19 by one rank such that the TFBGA can be arrayedat 1.2 mm square.

Although the inventions which have been made by the inventors arespecifically explained in conjunction with several embodiments, it isneedless to say that the present invention is not limited to theabove-mentioned embodiments and various modifications are conceivablewithout departing from the gist of the present invention. For example,the memory LSI may be, besides the above-mentioned SRAM, a dynamic RAMor a flush memory (EEPROM). The microcomputer LSI may be any type ofdigital signal processing circuit including a microprocessor or thelike. The present invention is, besides the above-mentioned stackedpackage LSI, widely applicable to a semiconductor device which mountsone semiconductor chip on a substrate and adopts a package of BGAconstitution.

To briefly explain advantageous effects obtained by typical inventionsamong the inventions disclosed by the present application, they are asfollows. The semiconductor device uses the package substrate on whichthe bonding leads which are formed respectively corresponding to bondingpads for address and data which are distributed to the opposing firstand second sides of the memory chip, and the address terminals and dataterminals which are connected to the bonding leads are formed. Thesemiconductor device further includes the address output circuit anddata input/output circuit which are also served for memory access andthe signal processing circuit having the data processing function. Thesemiconductor chip in which the bonding pads which are connected to thebonding leads corresponding to the address terminals of the packagesubstrate and the bonding pads which are connected to the bonding leadscorresponding to the data terminals of the package substrate aredistributed to two sides out of four sides and the above-mentionedmemory chip are mounted on the package substrate in a stacked structure.Accordingly, it is possible to suppress the pull-around of wiring layerson the substrate package to a minimum. It is also possible to make thecontour size of the semiconductor device as small as possible. Further,since the connection of wiring layers can be performed both of the frontand rear layers, it is possible to use the thin and inexpensivesubstrate.

1-14. (canceled)
 15. A semiconductor device comprising: a wiringsubstrate including a plurality of bonding leads; a memory chip mountedover said wiring substrate, said memory chip having a plurality of firstbonding pads; a microcomputer chip mounted over said memory chip, saidmicrocomputer chip having a plurality of second bonding pads, an addressoutput circuit serving for memory access, a data input/output circuitserving for memory access and a signal processing circuit having a dataprocessing function, a plurality of first wires electrically connectingsaid plurality of first bonding pads of said memory chip with saidplurality of bonding leads of said wiring substrate; a plurality ofsecond wires electrically connecting said plurality of second bondingpads of said microcomputer chip with said plurality of bonding leads ofsaid wiring substrate; and a resin body sealing said memory chip, saidmicrocomputer chip, said plurality of first wires and said plurality ofsecond wires; wherein said plurality of first bonding pads of saidmemory chip are exposed from said microcomputer chip.
 16. Asemiconductor device according to claim 15, wherein said memory chip hasa first side and a second side longer than said first side; wherein saidplurality of first bonding pads of said memory chip are located alongsaid first side; wherein said microcomputer chip has a plurality ofsides; and wherein said second side of memory chip is longer than eachof said sides of said microcomputer chip.
 17. A semiconductor deviceaccording to claim 16, wherein said second side of said memory chip islonger than all sides of said microcomputer chip.
 18. A semiconductordevice according to claim 16, wherein said microcomputer chip is squarein plan view.